Sheet feeder

ABSTRACT

A sheet feeder having a conveyer for feeding sheets spread apart so that the corresponding transverse edges of adjacent sheets overlap each other; a singling station at the front end of the conveyer; a separating mechanism above the conveyer and preceding the singling station and comprising a suction head for lifting the rear edge portion of the leading sheet; and a separating blower for blowing an air current between the lifted rear edge of the leading sheet and the next lower sheet; and control means for the separating mechanism comprising a feeler element adapted to engage with a transverse edge portion of the leading sheet and to insure that this sheet will not be sucked up by the suction head until its front edge is located at the singling station.

United States Patent 1 1 Kistner 1 1 Mar. 2 7, 1973 [54] SHEET FEEDER Primary Examiner-Even C. Blunk [75] Inventor: Hermann F. Kistner, 7141 Neckarj i 'g gii f Stoner weihingen, Germany uomey rt ur em [73] Assignee: Maschi'nenbau Oppenweiler Binder [57] ABSTRACT &C.O n lle,Gmn

o wel r er a y A sheet feeder having a conveyer for feeding sheets Filedi 1970 spread apart so that the corresponding transverse [21] Appl. No.: 77 ,124 edges'of adjacent sheets overlap each other; a singling station at the front end of the conveyer; a separating mechanism above the conveyer and preceding the sin- C 271/62 C gling station and comprising a suction head for lifting Int. Cl. the rear edge portion of the leading sheet; and a Field Search 62 C separating blower for blowing an air current between the lifted rear edge of the leading sheet and the next References Clted lower sheet; and control means for the separating UNITED STATES PATENTS mechan sm comprising a feeler elernent adapted to engage with a transverse edge portion of the leading 1,760,119 5/1930 Cross et a1 ..271/37 sheet and to insure that this sheet will not be sucked 2,082,239 6/1937 Belluche et 7 up by the suction head until its front edge is located at CI'OSS the tation 2,127,714 8/1938 Belluche ..271/38 7 Claims, 3 Drawing Figures Patented March 27, 1973 3,722,878

2 Sheets-Sheet 2 lnvenfor: Hermann K/S THE? snEET FEEDER The present invention relates to a sheet feeder, and more particularly to a continuous feeder, which is provided with a sheet-singling position or station at the front end of a conveyer which is adapted to move the sheets in a scalelike relation in which their transverse edges overlap each other in the feeding direction, and with a separating mechanism which is located above the conveyer and is provided with a separating blower and a suction head which is spaced from the singling station at a distance larger or smaller than the length of a sheet and, if desired, may be movable vertically to the conveyer.

For feeding especially large numbers of sheets to machines in which they are worked upon in any desired manner, for example, to folding machines, itis generally preferred to employ continuous feeders which permit a continuous uninterrupted feeding operation. In such feeders, the sheets are placed by hand in a scalelike overlapping relation upon an upper conveyer and they are then fed by conveyer belts around a turning drum to a lower conveyer and to a singling station thereon where the front edge of the uppermost sheet acts upon a feeler element which controls the movements of the conveyer belts and the feeding of the sheets in a scalelike formation in accordance with the removal of the sheets from the singling station. These known feeders have the disadvantage that, due to the manual depositing of the sheets upon the upper conveyer and the conveying operation including that of conveying the sheets around the turning drum, the distance of the overlap between the adjacent superimposed sheets will vary and deviate more or less from a certain normal distance. This fact is especially of disadvantage if, as usual in the known sheet feeders and especially in most pile feeders, a separating mechanism is provided adjacent to the rear edge of the first and uppermost sheet on the conveyer for improving the separation of the sheets from each other. This separating mechanism comprises a suction head which is adapted to act upon the rear edge portion of each sheet and operates automatically. When a sheet is withdrawn by the action of a suction wheel of a singling mechanism upon the front edge portion of the sheet, the suction head is opened and the vacuum is immediately eliminated which was formed as long as the suction head was closed by the sheet. The suction head is then lowered upon the stack of sheets under the action of a spring and sucks up the next sheet which again closes the suction head and produces a vacuum which causes the suction head with the sheet thereon to be lifted. One purpose of lifting the rear edge of the sheet is to pass this rear edge along wiping brushes for preventing the next lower sheet from adhering to the sheet to be lifted and from thus being likewise lifted. A second purpose of lifting the rear edge of the sheet is to permit a strong current of air to be blown between the lifted sheet and the following sheet of the stack for immediately separating the lifted sheet completely from the stack and for insuring that this sheet may then be be gripped at the desired part, that is, directly adjacent to itsrear edge, but at a part which is spaced at a larger distance from the rear edge. After this sheet has been sucked up by the suction head, it will not be further conveyed which has the result that the front edge of this sheet will never reach the singling station and the suction wheel of the singling mechanism therefore cannot grip the front edge portion of this sheet, but it will rather grip the next lower sheet which slides freely underneath and past the sheet on the suction head up to the singling station. Since this next lower sheet will not be acted upon by the current of separating air and the separating mechanism will remain inoperative since its suction head remains closed by the uppermost sheet which continues sticking thereon, the proper operation of the feeder can no longer continue.

it is an object of the present invention to provide a sheet feeder with a separating mechanism which will operate properly even though the successive sheets are spaced at longer than the normal distances from each other.

For attaining this object in a sheet feeder of the type as first described above, the present invention provides control means for the separating mechanism which comprise a feeler which is adapted to engage with one of the transverse edge portions of the sheet to be separated and which insures that this sheet will not be sucked up by the suction head until its front edge is located at the singling station.

Since according to the invention the separating mechanism cannot become operative and suck up a sheet until it has been moved to the singling station, it cannot possibly occur that, if the corresponding transverse edges of two successive sheets are spaced at too large a distance from each other, the second sheet will not be fed up to the singling station but will be sucked withdrawn without danger that the next lower sheet might adhere to it.

If especially in a continuous feeder two successive overlapping sheets are spaced too far from each other, the next sheet following at too large a distance will not up previously so that its further movement up to the singling station will be prevented and the separating mechanism will be rendered inoperative.

According to one preferred embodiment of the invention, the feeler is adapted to engage with the rear edge'portion of the sheet to be singled out and is provided in the form of a hold-down element which is located between the suction head and the separating blower and at a distance from the singling station which is slightly longer than the length of a sheet. This results in the additional advantage that, even if the distance between two successive sheets is too small as compared with the, intended normal distance, there will be no danger that the sheet feeder might not operate properly because the second sheet following the first sheet at too short a distance might also be sucked up, especially whenthe sheets are permeable to air, since the rear edge portion of the following sheet cannot be sucked up by the suction head until the rear edge of this sheet has moved past the hold-down element.

Since separating mechanisms for continuous sheet feeders cannot be provided with stripping brushes as often provided in pile feeders, it is advisable to design a continuous feeder in such a manner that the suction head after sucking up a sheet will carry out a pivoting or tilting movement in the upward direction and that it will be returned to its lower position under the action of a spring when the sucked-up sheet is drawn off by the suction wheel of the singling mechanism. This pivoting or tilting movement has the effect that a sheet which is to be sucked up will not jump up against the suction head merely because of the suction exerted by the latter, but will thereafter be additionally lifted off the next lower sheet so as to permit a better entry of the separating air current between the two sheets. According to a preferred embodiment of the invention, it is of considerable advantage in a sheet feeder of this type which is provided with a movable suction head to secure the hold-down element to the suction head in such a manner that, when the suction head is lowered, the hold-down element will pass in front of the nozzle .opening of the separating blower and screens the latter and thus deflects the air current emerging therefrom. The nozzle of the separating blower is therefore not closed up and the blower may remain continuously in operation since the separating air current will not prevent the top sheet from being sucked up against the suction head.

The features and advantages of the present inventio will become further apparent from the followingdetailed description thereof which is to be read'with reference to the accompanying drawings, in which FIG. 1 shows a side view of a preferred embodiment of the sheet feeder according to the invention and also diagrammatically and in dotted lines a modification of the invention;

FIG. 2 shows an enlarged view of a part of the sheet feeder according to FIG. 1, in which the separating mechanism is pivoted so that the suction head is in a lowered position; while FIG. 3 shows another view of the separating mechanism according to FIG. 2, but pivoted so that the suction head is in its raised position.

As illustrated in the drawings, the continuous sheet feeder according to the invention comprises an upper conveyer belt 18 upon which sheets 19 are deposited by hand in a scalelike overlapping relation, a turning drum 20 and a lower conveyer belt 21 upon which the sheets are deposited in a row by the turning drum 20. While the sections of the conveyer belts 18 and 21 which carry the sheet 19 extend horizontally, they pass in semicircular arcs around the turning drum 20 so as to form a channel between them through which the sheets 19 are passed.

Immediately behind a guide roller 22 for reversing the lower belt 21, as seen in the conveying direction of this belt, the sheet feeder is provided with a sheet singling station 17 which is provided with a feeler element 14 which, when moved by its engagement with the front edge of a sheet, operates a switch or the like to switch off a drive mechanism (not shown) for the conveyer belts 18 and 21.

Above the guide roller 22, a suction wheel 5 ofa singling mechanism is mounted, the other parts of which are not shown. By means of this suction wheel 5 the leading sheet 4 which is to be singled out is gripped when the front edge of this sheet arrives at the singling station 17. This sheet may then be further conveyed to another machine, not 'shown, for any desired operations thereon.

A horizontal support 26 which is mounted on and connects two uprights 24 and 25 of the sheet feeder carries a separating mechanism 27 which is located above the lower conveyer belt 21 and approximately at a distance equal to the length of a sheet from the singling station 17. This separating mechanism 27 comprises a suction head 2 on the free end of an arm 28 of a bell crank 29 of a rectangular shape which is pivotably mounted at its apex so as to be pivotable about a horizontal axis 10. The free end of the other arm 23 of hell crank 29 is pivotably connected to one end of a piston rod 30 the other end of which is secured to a piston 6 which is slidable within a cylinder 12. The front end of cylinder 12 is connected by a conduit 31 to a source of suction 16, for example, to a suction pump. By means of a spring 11 which is connected to the arm 23 of bell crank 29, piston 6 will be held in its rear end position in cylinder 12 if the suction head 2 is not closed, even though the suction source 16 is in operation. In this rear end position of piston 6 and piston rod 30, arm 23 projects vertically upwards, while the other arm 28 of bell crank 29 extends horizontally. Since in this position the suction head 2 is located at a shorter distance than the length of a sheet from the singling station 17, it will be located-only at a distance of a few millimeters above the rear edge portion'of the uppermost sheet 4, the front edge of which is located at the singling station 17. However, suction head 2 will then be located below the pivot axis 10 of bell crank 29. Behind the suction head 2, as seen in the feeding direction, a separating blower 3 is located which is constantly supplied with compressed air and the nozzle of which extends in the forward direction. The separating air current emerging from the nozzle of blower 3 extends at a small angle to the conveying direction of the conveyer belt 21 and the sheets thereon, and the nozzle opening is likewise located only a few millimeters above the sheets and spaced from the singling station 17 at a distance slightly larger than the length of a sheet. At both sides of the nozzle of the separating blower 3 two pressure rollers 9 are rotatably mounted on the front ends of two arms 32 which are pivotably mounted and pressed downwardly by springs and prevent the uppermost sheet from being sucked upwardly prematurely by the suction head 2 before the front edge of this sheet reaches the singling station 17. The entire separating mechanism 27 is supported by a roller 13 which rolls along the stack of sheets on the lower conveyer belt 21.

The mode of operation of the sheet feeder as previously described is as follows:

It is at first assumed that the sheet feeder is in the position as illustrated in FIG. 3, in which the front edge of the uppermost sheet 4 is located at the singling station 17 where it has actuated the feeler element 14 so as to stop the lower conveyer belt 21, while the rear part of this sheet 4 is sucked upwardly by the suction head 2 and then bends slightly around the bell crank 29 underneath its pivot axis. 10. The separating blower 3 then blows a current of air between this sheet 4 and the next lower sheet 33 so as to lift the sheet 4 entirely off the sheet 33. Thereupon the suction wheel 5 is acmined and grips the front edge portion of sheet 4- and draws the same off the suction head 2 in the direction toward the machine (not shown) which is to carry out any desired operations on this sheet. Since the suction head 2 is then free, air is drawn into it which causes the piston 6 under the action of spring 11 to move to its rear end position in cylinder 12 and the suction head 2 to pivot downwardly with the arm 28 of bell crank 29. While this pivoting movement proceeds, the lower conveyer belt 21 moves the next sheet 33 up to the singling station 17 so that the rear end of this sheet 33 is withdrawn from the pressure rollers 9 and is then sucked upwardlyagainst the suction head 2. Since the suction head 2 is hereby closed, the suction source 16, for example, a suction pump, will then produce a vacuum in cylinder 12 which causes the piston 6 to move forwardly from its rear end position in cylinder 12 against the action of spring 11. Arm 28 of bell crank 29 together with the suction head 2 and the sheet 33 thereon will then pivot upwardly about the axis 10. Thising to the invention can operate properly only if the rear edges of the successive sheets 4 and 33 are not spaced from each other at a distance smaller or larger than acertain predetermined distance. According to a preferred embodiment of the invention, the separating mechanism 27 is therefore provided with a hold-down element 8 which is secured to the free end of the arm 28 of bell crank 29 and, when the latter is in its normal position as shown in FIG. 2, projects vertically downwards between the suction head 2 and the separating blower 3 and in front of the nozzle opening of the latter to a level above and spaced a few millimeters from the section of the lower conveyer belt 21 which carries the stack of sheets 33. This distance should, however, be large enough to permit the sheets to travel past the hold-down element 8. It is further important that the distance between the position of the singling station 17 and the lateral surface of the holddown element 8 facing the latter will not exceed the length of a sheet by more than a few millimeters. This prevents the occurrence of any interferences in the operationof the sheet feeder even though the distance I between the rear edges of two successive sheets is larger or smaller than'a predetermined distance which may be of any desired size since the hold-down element 8 will not release the rear edge of the respective uppermost sheet for being sucked upwardly by the suction head 2 until the front edge of this sheet is located at the singling station 17.

According to a second embodiment of the invention as indicated diagrammatically in dotted lines in FIG. 1, the suction source 16 does not produce continuously a suction in conduit 31 but only at certain times which are controlled by a control element which is actuated by the feeler element 14 which is provided in the form of a feeler tongue. Thus, there will be no suction produced'in the suction head 2 until the front edge of the uppermost sheet which is to be separated from the other sheets arrives at the singling station 17. If therefore two successive sheets are spaced at too large a distance from each other, the second of these sheets will be prevented from being sucked upwardly before its front edge arrives at the singling station 17.

The two embodiments of the invention as previously described may also be combined with each other to provide for a maximum of operating security of the sheet feeder.

Although my invention has been illustrated and described with reference to the preferred embodiments thereof, I wish it to be understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed my invention, what I claim is:

1. In a continuous sheet feeder having a conveyor for advancing a bank of sheets in one direction, said bank being fanned-out on said conveyor, and said feeder having further a sheet withdrawing means for the topmost sheet of said bank and a separating mechanism mounted above said conveyor for separating the topmost sheet from said bank and for supplying the separated mechanism comprising a suction head for sucking up the rear end of the topmost sheet of said bank, and a drive means for reciprocally moving said suction head between a lower and an upper position being respectively closer and farther spaced above said conveyor, said drive means comprising a cylinder in which a piston is reciprocally mounted, said piston being operatively connected to said suction head so as to lift said suction head to said upper position when blower mounted upstream of said suction head for blowing a separating air current in said advancing direction between said bank of sheets and the topmost sheet lifted by said suction head in its upper position, a

control means for controlling the separating of the topmost sheet, said control means comprising a feeler element arranged in front of and downstream of said blower adapted to indicate a predetermined position of a transverse edge of the topmost sheet, and a preventing means which prevents, that this topmost sheet will be sucked up by said suction head before said topmost sheet has reached said predetermined position.

2. A continuous sheet feeder as defined in claim 1, in which said feeler element being arranged between said suction head and said blower also forms said preventing means, said feeler element having a transverse edge portion for preventing the sucking up of said topmost sheet by said suction head in its lower position before the rear edge of said topmost sheet has passed said transverse edge portion.

3. A continuous sheet feeder as defined in claim 2, in which said feeler element is reciprocably movable between a lower position and an, upper position in timed relation with respect to the movement of said suction head, said feeler element further forming a screen which in said lower position screens the nozzle opening of said separating blower so as to deflect the air current from said topmost sheet.

4. A continuous sheet feeder as defined in claim.3, in which said feeler element is secured to said suction head.

5. A continuous sheet feeder as defined in claim 4, in which, when said suction head is lowered, said feeler element engages from above upon the bank of sheets.

6. A continuous sheet feeder as defined in claim 1, in which said feeler element forms a tongue which is mounted adjacent to said withdrawing means and which is adapted to feel the leading edge of the sheet to be withdrawn, and said control means comprising further a control element being adapted to control a suction source producing the suction of said suction head.

7. A continuous sheet feeder as defined in claim 6, in which said feeler element is adapted to actuate a switch for controlling the feeding movement of said conveyor. 

1. In a continuous sheet feeder having a conveyor for advancing a bank of sheets in one direction, said bank being fanned-out on said conveyor, and said feeder having further a sheet withdrawing means for the topmost sheet of said bank and a separating mechanism mounted above said conveyor for separating the topmost sheet from said bank and for supplying the separated mechanism comprising a suction head for sucking up the rear end of the topmost sheet of said bank, and a drive means for reciprocally moving said suction head between a lower and an upper position being respectively closer and farther spaced above said conveyor, said drive means comprising a cylinder in which a piston is reciprocally mounted, said piston being operatively connected to said suction head so as to lift said suction head to said upper position when said suction head has sucked up the topmost sheet and is then closed by engaging the topmost sheet, said separating mechanism comprising further a separating blower mounted upstream of said suction head for blowing a separating air current in said advancing direction between said bank of sheets and the topmost sheet lifted by said suction head in its upper position, a control means for controlling the separating of the topmost sheet, said control means comprising a feeler element arranged in front of and downstream of said blower adapted to indicate a predetermined position of a transverse edge of the topmost sheet, and a preventing means which prevents, that this topmost sheet will be sucked up by said suction head before said topmost sheet has reached said predetermined position.
 2. A continuous sheet feeder as defined in claim 1, in which said feeler element being arranged between said suction head and said blower also forms said preventing means, said feeler element having a transverse edge portion for preventing the sucking up of said topmost sheet by said suction head in its lower position before the rear edge of said topmost sheet has passed said transverse edge portion.
 3. A continuous sheet feeder as defined in claim 2, in which said feeler element is reciprocably movable between a lower position and an upper position in timed relation with respect to the movement of said suction head, said feeler element further forming a screen which in said lower position screens the nozzle opening of said separating blower so as to deflect the air current from said topmost sheet.
 4. A continuous sheet feeder as defined in claim 3, in which said feeler element is secured to said suction head.
 5. A continuous sheet feeder as defined in claim 4, in which, when said suction head is lowered, said feeler element engages from above upon the bank of sheets.
 6. A continuous sheet feeder as defined in claim 1, in which said feeler element forms a tongue which is mounted adjacent to said withdrawing means and which is adapted to feel the leading edge of the sheet to be withdrawn, and said control means comprising further a control element being adapted to control a suction source producing the suction of said suction head.
 7. A continuous sheet feeder as defined in claim 6, in which said feeler element is adapted to actuate a switch for controlling the feeding movement of said conveyor. 